There is a growing consensus among researchers in evolutionary
computation that the discovery and separation of genetic modules
can make complex structures easier to evolve
by restructuring the genotype-phenotype
map, and also by allowing genetic material to
be reused. Many such systems follow the philosophy that
effective reuse can be achieved by first discovering or building
useful modules, and then duplicating them in the phenotype after they
have been discovered.
We believe that the duplication of genetic modules is not the primary
evolutionary factor leading to reuse of phenotypic structures.
Instead, natural evolution first establishes a morphological convention,
such as bilateral symmetry, and then exploits that convention
as a framework for repetition of phenotypic features.